


Tropical Punch

by bun_o_ween



Category: Voltron: Legendary Defender
Genre: Anal Fingering, Dubious Consent, Keith goes into heat and basically Shiro dorks the fuck out, Keith sniffs a weird flower and gets hella horny, M/M, Sex Pollen, Shiro panics, Size Difference, Size Kink, stupid boys hopelessly pining for each other, this is actually a love story, with filthy beginnings
Language: English
Status: In-Progress
Published: 2018-09-09
Updated: 2018-12-11
Packaged: 2019-07-10 03:53:18
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 9,462
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15941240
Author URL: https://archiveofourown.org/users/bun_o_ween/pseuds/bun_o_ween
Summary: If Shiro were to compare the universe and Keith, the boy would always win. There was no comparison. One was terrifying, sorrowfully beautiful, unexplored, and deadly.The other was outer space.





	1. Chapter 1

**Author's Note:**

> This is my first Voltron fic, and I would really appreciate y'all letting me know if you enjoyed this by leaving a comment or a kudos. I'm really nervous, so show me some love. Hope you like this!!

The heat was unlike anything Keith had felt before.

It was more _wet_ than hot. The kind of damp that clung to the red paladin’s throat and stuck his hair down to his forehead. Even the ground beneath his boots was warm and malleable, condensation covered leaves squishing as he stepped on them, plants wilting and simultaneously thriving as Keith tread through the muggy jungle.

“You find anything yet?” Keith asked into his receiver, the hint of static in his helmet the only sign of technology around him. The noise flickered, spluttered up against the young man’s ear as his teammate checked in.

“Yes,” Lance announced. “Leaves. Lots of leaves.”

Keith growled, and he stepped a little too hard on an unsuspecting thicket of flowers. It was just the two of them out here, pushing through ferns that looked earth-like, but at the same time… _didn’t_. He and Lance had been tasked with seeking out a beacon, a distress signal they picked up as they passed over the planet which Allura described as _seemingly benign_.

But the thick vegetation messed with their tracking system the moment they touched down, leaving the team to wander out in five seperate directions. He and Lance were on the west side of the jungle, and if Keith concentrated he could hear Lance’s graceless footsteps somewhere distant to the left of him.

“Well let me know when you see something _other_ than leaves,” Keith hissed, closing his eyes a minute to keep himself from losing it.

By now the planet’s suns were directly overhead, and everything was soaked in some kind of condensation. The leaves dripped, and the ground melted, and Keith’s helmet was beginning to collect a thin sheen of fog around the inside. He stopped to catch his breath, staring up at the blinding suns. His armour was heavy. He hadn't slept right in days. He wanted to sleep.

But first he had to find the distress beacon.

Lance was humming something through their helmets. His voice was low, and often slipped in and out of range. Keith didn’t mention it, didn’t really mind. If he was honest the sound of Lance singing wasn’t as horrible as the best deafening song of cricket-like insects infesting the planet. It made him feel less alone. Like he weren’t heading deeper into a world unexplored by mankind.

After an hour or so he came across a clearing. The sun and heat made the air foggy, the plants glistening as Keith stepped into the opening and looked around. By now he was panting, breath fogging up his helmet. His eyes stung with sweat as he scrunched up his face, unable to wipe away the perspiration with his hand.

There were flowers everywhere. In every colour imaginable, and some in colours Keith had never seen before. His breath caught on sight of them, and spellbound for a moment he dropped down to his haunches, brushing a magenta petal with his glove. It dripped and swayed under his touch, vibrant yellow stamen bobbing in the thick air. It was the same size as his hand, and twice as bright as the others. Keith couldn’t take his eyes off it, and found himself transfixed.

“Lance,” he said, swallowing thickly. “You see any flowers on your end?”

Lance’s humming, which had become static background noise, stopped and turned into a thoughtful sound.

“Yeah, lots of flowers here,” Lance said back. Keith continued staring at the swaying flower, tracing it's stem with the underside of his finger.

“Any, _uh_...” He trailed off, frowning. “Any pink ones?”

Lance laughed, and if Keith listened closely he could hear the other man breathing heavy in his helmet too.

“No pink ones here, buddy. Why, you find something?”

A breeze rippled over the meadow Keith sat in, and although he couldn't feel it through his suit he could see it lift the pollen off the flowers, and shake the leaves from the trees.

He'd give _anything_ to feel it on his skin.

“Keith?” Lance tried again. Keith didn’t respond, his fingers going to the seam of his suit and helmet.

“I'm going to take my helmet off,” he mumbled, blindly searching for the latch.

“Keith,” Lance laughed, too loudly. A pause. “ _Wait_ , Keith. Are you serious? Allura specifically said _not_ to take off your helmet. We don’t know-”

He was interrupted by a loud hiss.

Keith’s helmet disconnected from his shoulders, a puff of cool air treating his balmy throat before he pulled it up off his head and settled it down in the grass. He could hear Lance talking, distant and muffled amongst the smaller, technicolour blossoms, but he paid it no mind. The wind felt sweet on his skin, cool and rewarding in the steamy air, and he wasn’t sure if Allura had got it wrong, or if it was his Galra heritage, but Keith could _breathe_.

He closed his eyes, the breeze tickling his damp hair, brushing over his cheeks. The air was fragrant with pollen, sticky sweet and tropical, and the young man lowered himself to his knees, a content hum escaping his lips. There were birds, or something like birds, chirping in the distance. It felt enough like home that he could forget the danger of the situation for a moment, happy to kneel there and cherish the wind on his sweaty skin.

And then he noticed the magenta flower, bobbing patiently before him.

His glove came off next, gripped between his teeth, fingers wiggling as he celebrated the removal of the damp fabric. He reached out for the pink petals, tracing them this time with bare fingers. His head was heavy, body gooey. He was faintly aware of _something_. A droning. A distant, primal warning not to touch, not to interact. But it quickly dissipated as he flirted with the petals, and the petals swooned under his touch.

“Can you smell that?” Keith wondered out loud. Lance’s reply was lost under the space cicadas, the blood rushing to Keith’s head. Lance sounded urgent and annoying. It made Keith frown.

He opened his mouth to complain, but was cut off when the large flower shivered, and expelled a thick spray of pollen directly at his face.

Keith fell back on his ass, wiping frantically at the spray of pores that filled the air and plastered to his cheeks. He inhaled them through his mouth, and in his nose. They stuck to his sweat, and his armour, and drifted past him in the wind, so dense that while Keith came to his senses all he could see were thousands of yellow, fairy-like speckles in the air.

“ _KEITH!_ ”

Lance’s voice sounded a lot louder than before. Keith could only stare as the pollen dissipated, wheezing so rough he spat some of it out. But he could feel the rest inside him, making his nose twitch. A hand grabbed his shoulder and Keith flinched, whipping around to see Lance staring at him, eyes wide and alarmed.

“What the quiznak Keith?!” Lance’s voice was high-pitched and panicked.

“I just...” Keith trailed off. “I needed to breathe.”

Lance stared at his face, his pollen-smattered hair, slowly shaking his own head, which was wisely still inside his helmet.

“Did that thing throw up on you?” He asked in awe, mouth hinting at a smile.

“ _No_ ,” Keith growled, like the evidence wasn’t literally written all over his face. He stood up and took a step forward but his knees buckled, and he fell down on his hands and knees, all the air knocked from his lungs.

He could hear Lance talking. Could feel his hands go to his shoulders, squeeze against the armour, and the second skin of fabric, and they shook him. The Cuban's hand lifted his face, the dual suns hit his eyes and he closed them, swallowing. There was a lump in his throat. Insects in his stomach. He opened his mouth to tell Lance not to worry.

But he swayed, like the flower had, then wilted, and landed face forward in the _seemingly benign_ vegetation.

……………………………………………………………………………

 

He felt fine.

Or, at least he _thought_ he did. Ever since he and Lance made it back to the lions he'd been blinking spots out of his vision, stumbling in the thick grass and leaning heavily on the blue paladin’s shoulder. Inside Red he’d felt better, if not slightly flustered. He could pass that off as embarrassment, and not an effect of the space pollen.

Back at the castle things fell apart. Pidge yanked Keith down by his hair to shine a flashlight in his eyes, and Allura stuck something metallic and cold between his teeth. Lance was still shouting, and Hunk and Pidge were talking over the top of one another, while Coran scraped a sample of pollen off the paladin’s face.

“I told him not to take it off,” Lance kept yelling, accusatory. Keith tried to scowl but his face was whipped back and forth, examined and flooded with light. It made him feel worse. Head-light and anxious, and between the swimming dots and auditory assault, he could see Shiro staring with all the others, a crease between his brow.

Somehow his patient glaring spoke louder than the others.

“I’m fine,” Keith told him afterwards, the black paladin cornering him the instant they were alone. Allura had run off with the swab, the rest trailing after her, Pidge discussing Keith’s potential demise as if it were a new attraction at Disneyland.

Shiro looked him up and down, his arms crossed over his chest. His broad, _broad_ , stupidly firm, chest. The man was still frowning, his mouth half open like he was struggling to choose between his _best friend_ or _leader_ voice..

“But if you weren’t?” Shiro sighed, deflating a little. He was looking at Keith like he might break any second.

Everyone was worried for nothing. Keith had always been sensitive to flowers, a trait which had never bothered him in the desert. _I’m simply too sensitive_ , he reasoned with a blush. He stared over Shiro’s shoulder, feeling hotter than before.

“You'd be the first to know,” Keith promised, forcing a little smile on the corner of his mouth. Shiro glanced down at it, and then back to his eyes.

“Remember that time at the Garrison,” Shiro said, switching to his leader voice. “When you got sick and refused to admit it to anyone? You sneezed on the flight simulator and half the class got sick too. Then you went missing for a week. You lost weight, and got a fever…”

He trailed off when Keith cleared his throat, staring sheepishly at his friend. His _best_ friend. His… he stared for too long, heart swelling painfully against his ribs.

“I'd tell you, Shiro.”

The older man studied his face, his eyes dark in the privacy he made for the two of them. Keith stared back, as if to give validity to his lie. Eventually Shiro's shoulders fell, and he huffed, shaking his head.

“You look ridiculous,” the black paladin murmured, reaching out to press his thumb against the end of Keith’s nose. It made him flinch, skin tender and red from the pollen, and he swatted the man’s hand away. Shiro laughed, deep and handsome. His scar crinkled on the edges whenever he smiled.

“Shut up,” Keith mumbled, gritting his jaw so he wouldn’t smile too. He crossed his arms and turned his cheek, sick of being pawed at. Shiro grinned at that, his smile brighter than the sun, and just as hard to look at.

With a firm squeeze of his shoulder, Shiro brushed past Keith and back to the bridge, leaving Keith alone in the hanger. With the head of Voltron gone, Keith's heart sank into the hive of insects in his stomach, heavy, and far too warm.

……………………………………………………………………………

 

For the first time since Keith had know them, Pidge was lost for words.

They couldn't determine what the pollen had done to Keith, only that it had affected him in _some_ way. Keith didn’t need a swab to tell him that. He could feel it now, growing stronger by each varga. What had started as a fleeting, uneasy tickle in his stomach had developed into a fully fledged ache.

With his Galra blood there were a lot of unanswered questions. His biology, like the plants on the jungle planet, was human and at the same time... not. All he could do was press his lips together, stare at the neon screen Pidge flicked through, enlarged and explained, not absorbing a single word. He sighed, fingers clenching in the fabric of his paladin bodysuit.

“We should let the blades know,” Shiro suddenly announced, as if he could sense the red paladin’s unease. Coran nodded, twisting the end of his moustache.

“You’re right!” He declared. “Keith's biology is an enigma. Who knows what the pollen is doing to his insides. I think it’s best if he was momentarily returned to his own kind.”

Keith narrowed his eyes. “Own _kind?_ ”

But he was ignored, and before he could pout any longer they were contacting the rebel Galra base, and Keith was being ushered onto a small shuttle, the paladins sending him a sympathetic stare as he shivered in his bodysuit, hair still damp with sweat.

The last thing he saw was Shiro, before his breath fogged up the glass, and the shuttle slipped away from the castle.

……………………………………………………………………………

 

When he arrived at the base, things became drastically worse.

His knees gave out on him again, and Keith stumbled out of the shuttle and onto the cold floor of the base hangar. He felt a surge of humiliation in his gut when he heard gasps, and the floor beneath his palms trembled with urgent footsteps.

“ _Keith!_ ”

Keith was quivering, hot and cold. He could feel sweat stuck between his suit and his skin, his stomach tight and queasy, the horizon slipping in and out of focus. He tried to open his mouth to speak, but all he could manage was an embarrassing groan.

Kolivan was on his knees in an instant, scooping Keith into his arms. He pawed hair back off his face, and Keith narrowed his eyes to focus on the Galra leader. Kolivan’s face was bright with slow-dawning horror, his hand tightening where it gripped the boy’s hip. Despite his expression, and the gnawing fear in Keith’s gut, Kolivan’s broad shoulders and serious face were enough for Keith to blush again, his skin burning up under the touch of the older man.

“W-what’s going on?” Keith mumbled, noticing the other blades making a tentative circle around their leader. Kolivan was still giving him _that look_ , that terrifying look, and he leaned down to sniff at Keith’s sweaty throat. He recoiled instantly, pupils fat and black, his thumbs squeezing into the meat of the boy’s hips.

“Krolia!” He shouted, making Keith flinch. “Come get your son! _Now!_ "

He stood up, and Keith’s stomach sunk as he was suddenly six foot higher, fingers tightening in the male’s armour. Krolia darted out between the apprehensive circle, her own eyes bright and alarmed. Keith’s head lolled between them as he was palmed off to his mother, whose hands were surprisingly cold against his cheek.

“Mom,” he whined, eyes closed. There was something sweet in the air, clouding his logic. He pressed his nose to Krolia’s throat and shivered, trying to block it out.

“Krolia,” Kolivan warned again. “Get Keith out of here.”

Keith opened his mouth to argue, his hands weak circles around his mother’s wrists. The room felt as muggy as the jungle, air thick with that strange, thick scent. Keith sniffed at it, his head so heavy it fell forward to his mother’s shoulder. Her chest rumbled with her urgent voice but Keith paid no mind to it, pressing his forehead to her neck. Then they were walking, and the static of the panicked Galra was gone.

“ _Mom_ ,” he tried again, reaching for her face. His arm fell heavy against his chest, fingers twitching uselessly. She set him down somewhere dark, pressed a cloth to his head to ease the sweat from his brow. He noticed he was panting now, a new development. Krolia removed his shirt and patted his throat and chest, staring at him in mild awe, like he were covered in blood.

“I’m calling the paladins,” she announced. Keith’s heart skipped a beat.

“N- _no_ ,” he begged, trying to sit up. She pressed him down again easily, still drying his skin. His heart was hammering, skin prickled as he tried to speak, tried to sit up and prove he was okay, he was _fine_. But her next words stopped him cold.

“I’m calling them to come and get you,” she said again. “You smell like you’re in heat.”

For a second he said nothing.

Keith laid back against the metal cot, closing his eyes so tight he saw stars. He breathed in, shaking his head to try disperse the intoxicating smell he refused to believe was his own. He exhaled out his nose like he might shake the last of the pollen from his airways.

“In heat,” he mumbled, curling his arms around his waist. _That isn’t possible_. His knees pressed together and he coiled into a ball. “Am I going to die?”

He could have sworn Krolia laughed, but when he looked up she was as stoic as ever, her eyes narrowed as she analysed every inch of her shivering son.

“No, Keith.”

The boy whined, confused. “Then what’s the problem?”

Even his voice sounded wrong. Thick and sticky, like he swallowed a spoonful of honey. He was about to cry, he could feel it. The ache in his stomach was too visceral. His thighs pressed together so tight they burnt.

“You’re on a ship full of alpha males,” his mother said bluntly. “If you stay here any longer they will become unable to control themselves.”

She combed back a lock of Keith’s hair, her expression betraying nothing. Keith couldn’t breathe. He was staring back, mouth parted, sick with confusion. His cheeks burnt. His tongue thick with questions.

Eventually the tension in his stomach turned to cold fear as he realised what his mom was trying to tell him.

……………………………………………………………………………

 

He felt like a child.

When he was six, the school had called Keith’s dad to come pick him up because he’d gotten sick and thrown up in the playground. He never quite forgot the chastised, nervous feeling in his belly as he waited for his dad to arrive. How he felt on sight of him, simultaneously relieved and anxious, big hand on the back of his head, tousling his hair.

The situation he was in now felt similar, except he wasn’t sick. He was in heat, and Krolia wasn’t calling his dad. The video display before them flickered electric blue before Lance’s face popped up on screen.

“Mom,” Keith mouthed off camera, still hugging his waist. He glanced at Lance, eyes wide, and then back to his mother. “Don’t,” he mouthed. _Don’t embarrass me_. Krolia gave him a nod, as if to reassure him she'd use as much tact as possible.

“Keith is sick,” Krolia said to the screen, strictly business. Lance screwed up his nose, shaking his head like he had known this all along.

“It was that flower thing, wasn’t it?” He asked, shaking his head. “Did he get space hay fever, or something?”

Krolia glanced sideways at Keith. Keith shook his head.

“Something like that,” Krolia replied to Lance. “Someone needs to come retrieve him. _Now_.”

The determined lilt to her voice made Lance sit up straight, and his face fall.

“It’s that serious?” He breathed, and the way he said it made Keith swallow. He almost felt bad for the Cuban. Or perhaps it was the space pollen messing with him again.

“It’s direly serious,” his mom confirmed. “If he’s not removed, the entire ship…” She trailed off, sending another glance towards her son. “The entire ship might… get space hay fever.”

Keith exhaled in relief. For all he cared, his mother was now the _queen_ of tact.

“Oh, shit.”

Lance sounded inelegantly shocked, and Keith watched as he looked around the bridge like he wasn’t sure of what to do. Keith dug his fingers into his suit, and felt that anxious feeling, the same as the one he’d felt when he was six. He felt so bad it made him lean forward, catching his reflection in the holographic display. He looked dishevelled, his pupils more yellow than before.

“Lance,” he said, voice shaky. His tongue brushed against his canines, sharper than before. “Please don’t tell Shiro.”

He wasn’t sure of why he said it. It just came out, as sudden as his eyes and teeth. It felt worse now than he knew what was wrong with him. He felt damp, and slick, and wet between his thighs. The shame coloured his cheeks, made him swallow around the mortification. Lance stared at him, his eyes narrowing in a way that made him seem older.

“You’ve got it, buddy.”

His promise sounded so convicted that the nervous bundle in Keith’s stomach loosened slightly, and he fell back into his seat, breathing heavily. Krolia was still speaking to Lance, but Keith tuned them out, concentrating on keeping his head clear. With each passing dobosh he felt sicker, and warmer, and foggier. It was a struggle to stay upright. To stay lucid.

With the knowledge that someone was coming, _someone who wasn’t Shiro_ , he let his eyes close for a moment. The warmth was unforgiving. Like the jungle planet he’d contracted it from, it was familiar but terrifying. He wanted to escape it. He wanted to slip further into it, burning up until his spine liquified and his entirety melted.

The last thing he remembered was the black lion appearing on their radar, but by the time it came he was too out of it to feel betrayed. His mouth curled up a little, lips parted around the last syllable of Shiro’s name, and then he was fainting onto the control room’s floor, and everything turned black.

……………………………………………………………………………

 

Even at his worst, Keith was beautiful.

Shiro knew he had it bad when he looked at the red paladin, in this state, and thought he was the prettiest thing he’d seen in space so far. Keith was on his knees, pressed against a wall of glass, panting on the barrier that separated them. All ten of his fingers were pressed to the surface, his nose too. His eyes were glazed and luminescent, and when he widened his mouth to murmur Shiro’s name, the man could see how his teeth had sharpened too.

He was locked inside a tank. It wasn’t _exactly_ a tank, but Shiro had no other word for it. The glass cage was roughly six foot long, and extended floor to ceiling. There were no windows. No doors. Absolutely nothing inside, but Keith.

When Lance had told him something was wrong, Shiro had left without hesitation. Normally he was a rational man. Patient, and intelligent, and well aware of how risky behaviour could put others in jeopardy, could leave Voltron, the entire galaxy, vulnerable without him or the black lion.

But Keith had always made him stupid.

If Shiro were to compare the universe and Keith, the boy would always win. There was no comparison. One was terrifying, sorrowfully beautiful, unexplored, and deadly.

The other was outer space.

“He had to be contained,” Thace explained, looking somewhat embarrassed despite the lilac hair covering his cheeks. The black paladin nodded, watching as Keith - _spitfire, formidable Keith -_ crawled along the interior of the tank like an animal. Krolia was there too, all eyes on Keith as his fingers dragged down the tank wall with a squeak.

“The tank deprives him of scent,” Krolia explained, “and protects Keith from the smell of others.”

Shiro swallowed around the lump in his throat as Keith glanced up at the sound of his name. He made a sound, and his nose nudged against the glass. He drummed his fingers against the barrier, blinking slowly. His hair was slicked back off his face, cheeks pink with blood.

“ _Shiro_ ,” he murmured. The man shivered. He stepped closer to the glass, the Galra keeping their distance. If Keith really did smell, if he was really in heat, Shiro couldn’t tell. He was the only human on this base. The only _full_ human. He slid slowly to his knees, pressing his fingers against Keith’s through the glass.

“You can’t keep him in here,” he said, watching Keith stare at their fingers, his mouth open, his teeth small, and white, and sharp. _Like a kitten_ , he thought absently, breathing in so deep that he wouldn’t lose his mind and smile.

“We only want what’s best for Keith,” Kolivan suddenly spoke up, voice deep and commanding. “He’s like a son to us.”

Krolia cleared her throat. “He is my son.”

“He’s my-” Shiro stopped himself, withdrawing his fingers. Even in his drugged, semi-lucid state, Keith frowned. “He’s my best friend. He can’t be kept in a tank like an animal.”

Keith leaned in, opened his pink lips and flattened his tongue to the glass. He dragged it up the tank, leaving behind a slick trail of saliva. Thace cleared his throat. Kolivan muttered something under his breath. Shiro’s stomach turned, and heat uncoiled in his gut.

“That’s why we called for help,” Krolia said, stepping closer to the glass. Shiro stood, leaving Keith to glower at him from his feet, glass still wet with spit. “You can take him back to the castle. His scent won’t upset humans. It should not upset the Alteans either.”

“And his heat?” Shiro asked, unable to stop the flush of warmth that enveloped him when saying the word. He tapped his artificial finger to the glass, gaining the noirette’s attention.

“His heat will pass,” said Krolia. “It should not take more than a week, but he will need to stay contained. He will become subservient to his desires, sometimes violent. Especially as this is his first heat.”

Keith watched his finger as he traced the metal tip against the glass, leaning in until his nose bumped the glass again. Shiro made a circle and Keith followed, eyes narrowed in concentration. The man almost laughed, almost opened his mouth to say he doubted Keith could become violent in this state, but was cut off by a hungry, pretty sound.

With a moan, Keith opened his mouth again and licked the glass, right over the spot where Shiro pressed his metal fingers to it. His teeth elongated slightly. His breath clouded up the glass. The black paladin pulled his hand back like he’d burnt it, Keith’s inhuman eyes burning holes right through his head.

……………………………………………………………………………

 

A storm hit before he could take Keith home with him.

A celestial death storm, to be precise. One of the most terrifying and powerful phenomenon of the universe. It swept across their quadrant with the urgency in which Shiro had arrived himself, blocking off communications, and of course, their way back to the castle. He had no choice but to stay at the base while the storm passed over, so the Galra helped him drag a small cot into the room containing Keith’s tank so he could keep watch over him that night.

Shiro couldn’t sleep.

He had never been a perfect sleeper, not even before Kerberos. Anxiety kept him awake, staring at the ceiling night after night. Being kidnapped by the Galra, losing his arm, and crash-landing back on Earth hadn’t lessened those anxieties by any means. Neither did the fact Keith had gone into heat, and they were both far, far away from the closest thing to home they knew.

At some point someone had tucked a blanket and pillow into the tank, but Keith did not sleep. He continued calling Shiro’s name, like a caged siren, so dulcet and needy that the man stared holes in his datapad, districting himself with as many articles of Galra biology as he could possibly find.

Keith did everything he could to distract him.

It was hard to ignore him. Shiro told himself not to look. Not to feed the hungry, spellbinding vision of Keith waiting for him at the glass, still on his knees, still panting on the tank. He glanced up just to make sure Keith was still there. The paladin sighed, pressing his entire body to the glass.

“Shiro,” he whined. “Shiro, help me.”

He slid down the glass with a squeak, breathing like he’d been running. The pillow was bunched up under his thighs, pale linen against the black of his jumpsuit, the pink hue of his face and knuckles. His hips turned little circles over the pillow, concentric and slow, and borderline filthy. Keith was hard, and utterly unphased by it. It was enough to have Shiro glance furiously at his datapad, pressing his tongue into the side of his cheek.

“Shi-ro,” Keith huffed, becoming impatient. “Ta-ka-shi.”

Shiro cleared his throat, still scrolling but no longer reading. His entire being ached to look again, but he swallowed his desire and stared so hard at the datapad that his eyes dilated and ringing filled his ears.

“Fuck, Shiro. _Please_. I’m so wet.”

Shiro choked, dropping the datapad on the bed between his thighs. Keith was still pressed up to the glass, rutting his hips against the pillow like he wanted to get off. Shiro should have looked away, but he didn’t. It was impossible. He was trapped. He cleared his throat, mouth dry.

“W-what?”

“I’m wet,” Keith repeated, running his hands up and down his thighs. He pushed his fingers inwards, curling his spine out. One hand went to the collar around his throat, tugging at it to pull it down. In all his fumbling elegance, Keith managed to tug enough of the bodysuit down to show Shiro that his blushing wasn’t contained to his face. It went all the way down to his nipples, which were the same colour as his chewed at mouth.

“I’m s-so, _mm_.”

Keith’s eyes fluttered shut, a pained noise coming from the back of his throat. When he rolled his hips down again Shiro came to the startling realisation that Keith wasn’t trying to rut his dick up against the pillow. He wanted to be touched someplace else. Shiro’s heart rose to his throat and he scrolled desperately through the article, only stopping when he reached _reproduction_.

“ _Shiro_. Don’t you want to mate with me?” Keith begged.

His voice was not his own. It reminded Shiro that this wasn’t Keith. Keith wasn’t home. Keith was a prisoner to his own base biology, tormented by endless wave after wave of arousal. It didn’t stop the pathetic twitch of Shiro’s cock, already half-hard and pressed to the zipper of his pants.

“Don’t say that,” Shiro demanded. Keith stared like he could see right through him.

“Breed me,” Keith whispered, suddenly thumping his fist against the glass. “Let me out. Mate with me. Shiro. _Shi-ro_ , let me out.”

It was like the heat told Shiro everything he’d ever wanted to hear. It physically pained him to watch Keith, who was dancing slowly now, hips rocking side to side as he ran one hand against the glass, the other into his hair. His mouth was open, tongue out a little like it was hot inside the tank. Shiro bet his skin felt like fire, milky and pretty, but scorching. Enough to melt the metal of his artificial arm. He stood up and made his way to the glass, utterly consumed by Keith.

 _Keith’s eyes, Keith’s waist, Keith’s mouth, Keith Keith Keith_.

He pressed his organic thumb to the glass this time, watching Keith surge forward and kiss it against the glass, eyelashes fluttering down upon his cheeks. For a second the man allowed himself to trace the outline of Keith’s lip, the boy opening his mouth to indulge him, tongue wetting his berry mouth.

Shiro felt terrible because he should have been ashamed. Should have took his thumb away from Keith’s obscene mouth. Should have turned his back on the boy who would never allow this, never act this way if his brain wasn’t stuffed with cotton wool, who would never love Shiro the same way his tongue was loving the slick glass, never want him that badly that he cried for it.

He felt terrible because he should have left, but he didn’t. He kept staring, blood pulsing between his legs until his cock was thick with it, and he considered pressing it to the glass, seeing if Keith would chase it with his cherry lips, if his eyes would glaze over for the weight of it, upturned nose pink from pressing up against the dirty glass.

“Takashi,” Keith whined. “I _need_ you. I need you, please. Let me out.”

He thumped his fist on the glass again, and this time it knocked some sense into Shiro. He moved back a step, regretfully leaving only fingerprints on the glass. Keith bared his teeth, and his eyes narrowed back into golden slits.

“Let me out!” Keith said louder, smacking the glass. It echoed. Shiro’s eyes widened. “Let me out, Shiro! Let me out! Let me out!”

He smacked the glass, again and again, snarling like an animal. Shiro scrambled backwards, grabbing the datapad and calling for Kolivan, hitting the emergency button over and over, in perfect harmony with Keith’s vicious smacks against the glass. He would break it. His hands would bleed. Shiro shut his eyes, blocking out the sight, waiting for urgent footsteps in the hall.

Keith forced all sound out, screaming so loud it was raw, a wetness in his throat, unadulterated anger bleeding out every feature, suit still hanging down his shoulders. His crying tore the black paladin apart, ripped his heart out of his chest and crushed it. Bit into it with kitten-sharp teeth, tore it apart with deadly fingers, and eyes that consumed planets.

……………………………………………………………………………


	2. Chapter 2

**Summary for the Chapter:**

> In his dreams Keith had been a deity. In reality, Keith cried like a slut.

If Shiro closed his eyes he could imagine he was back home.

Not _home_ as in the decorated shell of memories back at the Garrison. Not _home_ as in the room that smelt like less like Adam and more like stale coffee with each day that passed.

No. If the man closed his eyes and took a deep breath, he could imagine he was back at the Castle, the constant whir of Altean engineering in the glossy white walls, the soft blue of the touch panels.

Even the noise of the celestial death storm outside could be mistaken for the lions. The occasional footsteps in the hall might have been Lance, or Hunk, or –

Shiro opened his eyes and stared at the tank across the room.

Keith stared back, his eyes the colour of unrest. As soon as he noticed the older man looking back, the half-Galran boy sat up on his knees and bumped his cheek against the clear barrier.

“ _Shiro_ ,” he mouthed, condensation on the glass.

His voice sounded raw and tired, and almost like regular Keith. If not for the sound of it, and his narrow canines, and his glowing eyes, and the _fucking glass tank_ , Shiro might have been able to pretend Keith wasn’t in heat too.

“Go to sleep, Keith.”

An hour ago Krolia had shown up and unlocked the tank. Keith had been hysterical, hot tears dripping down his cheeks as he screamed, demanded for Shiro, smacked against the glass so insistently that they’d all thought he’d either break through or pound his delicate hands into oblivion.

Krolia had pinned him to the floor like a puppy, jabbed a needle into the back of his leg. She had a scarf over her face but Shiro could see her nose wrinkled in displeasure. It made him draw closer, lean in as close as he dared, to try catch a smell of the elusive and seductive miasma Keith was apparently exuding.

“Don’t get too close,” Krolia warned, her hand easily encircling the girth of Keith’s thigh as she slid the needle from his skin.

The boy looked up through his hair, cheeks pink from crying, and stared at Shiro through the glass. He made a noise, his fingers curling as his eyes fogged over.

“What does he smell like?”

Krolia made a face.

“You can’t smell it?”

Shiro shook his head. He kneeled down as close as he dared and watched the struggle leave Keith’s body. His mother rolled him onto his back, tucked the crumpled pillow under his head of thick hair. She leaned down to kiss his head, and sniffed his cheek as she came up. It was a purely innate moment.

“He smells like...”

She trailed off, eyes soft. Her son watched her speak without coherency, an overwhelming calm taking over his features. Shiro had not seen Keith so relaxed, his eyebrows unknitting and eyelashes coming down to rest on his high cheekbones.

“He smells like Keith,” she settled. “Just... _more_.”

That sentence stayed with Shiro all night.

As he scrolled through his data pad, purposefully ignoring the luminescent eyes across the room, he could not help imagine what _more_ Keith would smell like.

Keith smelt like leather, and sunshine on warm skin, and on the rarest occasions that Shiro had been close enough to press his nose to the red paladin's throat – lemongrass scented soap.

Shiro stared right through the data pad and at his recumbent legs.

“Shiro. Come in here.”

If the man could stare a hole through the wall before him, he would have three hours ago. Keith’s voice rung out endlessly, his alien siren, using the tone he knew would lure Shiro in – hook, line and sinker.

“Why?”

There was no point in answering, but Shiro couldn’t help it. He wet his lips and looked back at Keith, his mouth glossy with spit.

“I want to see you.”

Through the haze of heat and tranquilliser, there was truth behind what Keith said. The gravity of it tugged at Shiro's heartstrings, toyed with something lower than his gut.

It took all his strength to remember why Keith could not be trusted outside the tank.

He would become _subservient to his desires,_ they had said. The words had not left the man’s head since hearing them.

More importantly, Shiro was not sure he could trust himself if he were to let Keith out of his cage.

A little voice inside Shiro wondered if the desires were bought on solely by Keith’s heat, or if there were a chance they could be fabricated from something lingering, something true...

His head hit the wall behind him as he forced his eyes closed, sucked in air as he steeled his heart and shook the thought right from his mind.

He couldn’t think like that.

Keith was sick. Keith wasn’t himself. Keith wasn’t thinking straight. Keith would never want him like that if he weren’t delusional.

Shiro opened his eyes to see Keith crawling over the pillow Krolia had bought him. His eyes were closed, cheek pressed to the glass, and he were grinding down onto the fabric like it pained him not to.

“It h-hurts,” he sobbed, lip catching on the condensation. “Takashi, it hurts so much.”

Shiro's prosthetic coiled so tight in the cot beneath him that the fabric tore. _Takashi_. That’s how he knew Keith were manic. The boy had never called him that before. Yet the rational thought did nothing to curb the ebbing desire stiffening in his pants.

“God, it’s killing me. I need you, Shiro.”

The sound of fabric, the slow grind of boy against feathers, made all sense stutter to a stop in Shiro’s mind. In his peripheral he could see it, couldn’t ignore it - Keith moving his hips in slow, desperate circles. They way he’d always imagined in his filthiest dreams. When his best friend was some forbidden figment that visited in dreams, left him waking hard and heavy with guilt.

He refused to turn, because if he did he would break.

Shiro swallowed past the baseball in his throat and opened another article on the data pad.

……………………………………………………………………………

 

“We offered him a mate, but he didn’t take it.”

Something hot coiled in Shiro’s gut at that sentence. Something didn’t really sit right. He looked up at Kolivan, clenching his jaw so he wouldn’t curl his lip.

“Who?”

Kolivan’s eyes lowered just enough to give Shiro his answer.

He scanned the table, the other Blades bowing their heads as if to acknowledge how dire the situation was. Shiro locked eyes with Krolia, who blinked back at the man with an unreadable expression.

“Kolivan was the most suitable candidate,” she said, as if Keith were not her son.

“But he didn’t accept,” added Kolivan.

The Blade leader's ears flicked back. In guilt, Shiro figured. Distantly, he wanted to laugh. Only Keith would turn down someone so powerful and revered.

“It's imperative that Keith finds a mate,” Krolia continued. “We did not think this was possible due to his human heritage. It’s likely this might never have happened if not for the...”

“Flower. It was a flower,” Shiro said, as if it mattered.

Krolia nodded, exchanging another look with Kolivan.

“In the midst of heat our kind is not usually so stubborn,” the woman said, and Shiro swore he saw her lip tremble. “But Keith has been alone for so long. He does not trust anyone.”

She lowered her head in a similar stance of shame to match Kolivan’s. All the Blades looked like they were at a funeral, gathered around the tactics table with Shiro at the head like they expected him to solve everything.

“How long can he last like this?” Shiro asked.

It made Kolivan look up, his eyes darting between the other members.

“I don’t...” He stopped, and swallowed. “I don’t know. Keith is an anomaly.”

Shiro stared down at his hands and squeezed his thumb into the bowl of his palm. He shook. The weight of the morning, the night before, buckled him over the strategy table. The muscles in his back bunched, his jaw ached from being clenched. He drew in a breath and it exhausted him, ate away at his thinly-spread restraint.

He looked up, and realised everyone was looking at him.

He could not admit that for the first time in his life, Shiro did not have an answer.

……………………………………………………………………………

 

Two cups of space-coffee and a message to the Castle later, Shiro found himself back at the tank.

Krolia was inside of it with Keith, one large hand cradling the boy's head. The other wiped tears off the paladin's face, his chest rising and falling with loud, dramatic sobs. When his head lolled back and met Shiro’s eyes, his breath hitched and his spine arched, his whole body rigid.

“Shiro!” He cried – voice so human it hurt.

Krolia whipped around and stared at Shiro through the glass, her teeth bared and her hair stuck to her cheek.

“You have to help my son,” she growled. “He’s in pain.”

She smoothed away Keith’s tears as he lay in her lap, still wearing his jumpsuit and writhing like an insect. His pupils were fat and black, his mouth open and sharp canines glinting in the low-lights.

“I can’t.”

Krolia’s face distorted into something feral. In the moment she looked more animal than Keith, all teeth and eyes and possessive fingers coiled around her precious son. The floor of Shiro’s stomach fell out, his arms useless by his side.

“You _can_. You're the only one he'll let touch him.”

She stood up, something shiny in her hand. An empty needle – Keith’s eyelids already drooping. At her full height she were terrifying, looming over the tallest paladin as she left the tank and cast one last worried look back to the boy.

“The sedatives are not working as they should,” she said softly.

She sounded defeated. Shiro could not take his eyes off the way Keith trembled.

“If he doesn’t find a mate he will go mad,” she told the man, neither of them looking at each other. “He could hurt himself. There have been Galra driven to taking their own lives when faced with unrequited want.”

Shiro’s heart clenched.

“Unrequited want,” he repeated.

Keith turned towards his voice and his body shook with another sob. His fingers pressed into the glass, slid down and squeaked.

“Shiro. It _hurts_.”

Fresh tears fell down his cheek. He didn’t look like a paladin. He didn’t look like a Blade. He looked like the same scared, malnourished fifteen-year-old Shiro had taken under his wing all those years ago.

The image, the pitiful sounds off his lips, drew Shiro to the tank. He took a deep breath and stepped in, watching Keith’s breath hitch, his eyes flicked with interest. When he stooped down to cup Keith’s face the boy worked his cheek into his palm as if it had always belonged there.

“They said you didn’t take a mate,” Shiro said.

Keith nodded, the end of his nose squished into the meat of his hand.

“I was too scared,” he admitted – something else Shiro never imagined hearing from his mouth.

And then another.

“I’m a virgin.”

Shiro hated how relieved he felt. He glanced up and it was as if Krolia could see into his mind.

 _Virgin. Virgin. Virgin_.

He felt each of Keith’s heartbeats in his fingers, his own blood cold and sluggish as he held the quivering boy in the cup of his hands.

“I always,” Keith hiccupped, “always thought. Thought when you came back from Kerberos that you -”

He stopped, hysterical with tears. His small hand went to Shiro’s arm, nails digging into the fabric of his shirt.

“That I what?”

From the corner of his eye he could tell Krolia was poised to kill him. He couldn’t move. His soul, his arms, in a deadlock of guilt, unbridled terror of hearing what Keith had to say next.

“That you’d come back to me,” Keith whined. “But you never came back.”

He started to cry. _Really_ cry. The type that broke Shiro’s heart. The kind that made him curl his arms around Keith’s body, draw him close as if to apologise for all the years he could never get back, all the promises he'd broken when he'd left for Kerberos.

Krolia raised her eyebrow as Keith curled his arms around him too, so exotic and intoxicating like the flower that made him like this.

 _See?_ She mouthed, watching her son become symbiotic. Shiro watched her leave, something horrible creeping up his spine.

She left Shiro alone with Keith.

Keith who was in heat.

This close he could smell it. _More_ Keith. Shiro pressed his nose to the crown of his hair, breathed in until his lungs were thick with it. Leather. Sun. Lemongrass.

Sex.

He went to sit up but Keith’s arms constricted like vipers. His nails dug into Shiro’s shoulder-blades, the boy’s mouth hot and wet against the column of his throat.

“Don’t go,” he begged, the edges of his words slurred again.

Shiro surrender to the touch, left with no choice when wide, glassy eyes blinked away the rest of the sedative.

“Shiro. _Please_ don’t go.”

Two hands went to each of his arms. Fingers slipped up the metal panel of his prosthetic, the others drew lines up his flesh shoulder. Both reached his biceps and stopped, and then squeezed.

Indulgently, Shiro flexed.

Keith’s eyes widened, and he laughed - surprised.

The sound made Shiro hot, worked the muscle loose from his shoulders. He let Keith drag him down until he was buckled over him, a willing prisoner in the boy’s possessive arms.

“You like that?” He asked, forgetting himself.

Keith’s eyes went black and he nodded.

“Yeah,” he breathed. “I like that.”

The cold horror came back, and Shiro stiffened. He watched Keith undulate between his arms, his own hands either side of his head. Thick hair brushed his knuckles, begged to be tugged. The boy chewed on his mouth, offered his lips like meat, something Shiro hadn’t had in a long, _long_ time.

“Keith.”

The boy’s fingers squeezed his arms again, his hips coiling into those dangerous circles he’d refused to watch last night. In the jumpsuit he was black leather, a flat stomach, thighs spread. His spine curled, lifted himself off the cool metal floor and pressed into Shiro’s rib with a pained, anxious sigh.

Shiro wondered if he might be part-Galra too, because the high-pitched noise that came from Keith was enough to have his heart stop. It got to him in a primal way. Drew him closer to the boy he knew he couldn’t touch. Keith had always been his Venus flytrap.

When Keith's hands slid down to Shiro's wrists, his palms were hot. He dragged the black paladin's hands down to his hips, and he instinctively curled fingers to the muscle there. Keith was narrow, small and masculine - but when Shiro clenched the flesh in both fists he could feel the promise of fat, the pretty swell of tender hips that had been the downfall of many hot-blooded males in the Garrison.

He felt balanced on a precipice. His heart wanted Keith to be happy. His brain screamed at him to run as far from the tank as he could.

His dick wanted to be buried in something tight and forbidden - to fuck, for the first time in years.

“K-Keith,” Shiro strained, struggling to hear his own thoughts over the throbbing of his heart. “You're in heat, Keith. You don't want this.”

Shiro was stronger than Keith. _Leaps and bounds_ stronger than Keith. But for all his muscle, all his weight, he couldn’t lift his hands from the boy’s fidgeting hips.

Shiro could feel the line he wasn’t meant to cross.

Physically feel it - pressed hard to his abdomen. Keith’s cock was searing warm even through the fabric of his jumpsuit. Pinpricks of claws curled into his flesh arm, scraped his metal bicep.

“Keith,” he said again, squeezing his eyes shut. “We can’t. Keith, we _can’t_.”

Even as the words left his mouth, Shiro knew he had already lost.

“ _Please_ ,” Keith whispered.

Shiro had never denied Keith before. As he looked from his black eyes to petal pink mouth he wondered, _why start now?_

He breathed in and the boy smelled as sticky and as sweet as the sounds he made. Shiro caved and slipped his hand between Keith's thighs.

“Mmnh- _hah._ ”

The material of the Marmora suit was butter soft, but Keith was hot and hard. His hips jerked up, nudged desperately into the bowl of Shiro’s hand.

“Baby,” he whispered. “Is this what you need?”

Keith writhed and shook his head, long hair sticking to his lips. With desperate hands he guided Shiro lower, pressed his fingers to his hole where it throbbed beneath the suit.

Shiro had dreamt about this before. How Keith would feel between his legs, the sounds he'd make when Shiro touched him there.

In his dreams Keith had been a deity. In reality, Keith cried like a slut.

There was nothing innocent about the noise he made when Shiro pressed the pads of his fingers against his entrance. He tested the fabric to see how far he could dig in before it pushed him back. His fingers came back wet, the fabric soaked through his something sharp-scented and slick.

Keith, like always, exceeded his expectations.

“U-uhhhh, _hah_.”

His head arched back, pretty throat strained against the fabric of his suit. Shiro wanted to kiss him, wanted to eat the nasty noises he made right off his mouth.

He pressed his lips into Keith's cheek and kissed him there instead, like it made him a better man, or forgave what he was about to do.

Keith looked like porn.

His milk-white thighs actually trembled as Shiro bunched the skin-tight fabric of the leggings down his hips. Keith’s cock, dark with blood and curved against the slick of his stomach, jumped at the hungry noise Shiro made.

His thighs were glossy with slick. Shiro stared down at him, transfixed by rose-pink flesh. His chest was still clad in leather and although every inch of Shiro longed to rip that off him too, he feared Keith would come to his senses any moment and push Shiro far away from him.

The boy sobbed when Shiro brushed his fingers over his wet, coiled hole. It'd been too long – _years_ , since Shiro had felt that, since he’d tasted the sharp spike of sweat between him and another body.

His finger slipped in easily and Keith, very suddenly, went silent. His fringe fell over his eyes and his body melted against the floor. The hands that had dug sharp pricks into Shiro's flesh now lowered to either side of his head. Submissive, and utterly sated by one knuckle buried deep in his cunt.

“More,” he mouthed, and Shiro was done for.

He was tight, and it rudely reminded the man above him that he was taking Keith’s virginity. Laid flat in a rebel fighter ship, dressed in a suit of armour while Keith wriggled in a leather bodysuit hadn’t been the way he’d pictured it.

But he buried his finger to the root and took it for his own, luxuriating in the tug of selfish need he felt deep in his gut. Keith clamped down and the man could only imagine how he’d feel around his cock, how pliable he’d be if he fucked him then and there.

Shiro closed his eyes and forced himself to breathe. He was doing this because Keith was in pain. He was doing it to _save_ Keith. He repeated the mantra over and over, but deep down he knew he didn’t need an incentive to fuck Keith.

He loved him. He always had.

He pressed his tongue to his cheek to catch himself from blurting it out, but even if he had he doubted Keith would remember. The boy was so delirious with need that Shiro doubted he’d have noticed if the entire Blade walked in at that moment.

 _Subservient to his desires,_ Krolia had warned.

It didn’t take much to make him cum. Shiro had barely slipped a second finger inside him when he suddenly seized, his spine curling up off the floor. The sight of his open lips, his ruddy cheeks, made Shiro want to kiss him again. But he simply watched instead, Keith’s orgasm like everything else he did. Violent, and hard to look away from.

“Keith.”

At first he didn’t respond. The boy blinked in slow-motion, turned and nestled into the forlorn remains of his pillow. Shiro pulled his fingers free, staring down at the flesh he’d fucked them into. He slipped both fingers between his lips and sucked, because why not? He’s going to hell anyway. They tasted like Keith, only _more_.

“Keith, please say something.”

The boy was watching him with heavy eyelashes, hardly fussing as he eased his crumpled leggings back over his hips. Shiro pressed a kiss to his beloved navel because the guilt became too much. He raised his head and smoothed back sweaty hair, revealing Keith’s relaxed brow.

“Shiro,” he said, the corner of his mouth curled up.

Shiro exhaled and watched him fall asleep. He watched longer still, the pleasant way Keith’s chest rose and fell. How his fingers curled against his cheek, eyelashes flutter in dream-state.

He didn’t deserve Keith.

He got to his feet and locked the glass tank behind him. The walls were smeared in fingerprints, fragments of pillow scattered over the floor like a mess. In the middle of it all Keith curled onto his side, as docile as a kitten.

Shiro sunk into the make-shift bed across the room and took care of himself in the dark.

……………………………………………………………………………

 

In the morning it was quiet.

Not quiet enough that the whir of engines could not be heard, or the distant footsteps of the Galra rebels disappeared. But it was quiet enough that Shiro woke with a chill, sitting upright in his cot.

Keith was awake, sitting with his knees against his chest.

He glanced up at Shiro and visibly relaxed, crawling to the tank wall and pressing his palm against the surface. His eyes weren’t glowing. His breath came out calmly, not in frantic little puffs. He frowned, a familiar expression Shiro associated with confusion.

“Shiro,” he said, voice deeper. The man’s heart stopped.

“I don’t know why I’m in here. I don’t remember anything.”

The tone of his voice should have made Shiro feel sick. The boy was nervous, trying poorly to mask the sound of his anxiety. He looked like hell, disheveled, and the man could only imagine how he felt.

But instead he felt full-bodied relief, and his heart kick-started in his chest.

  
  


**Notes for the Chapter:**

> If you enjoyed this please leave a kudos and come talk to me on Tumblr!

**Author's Note:**

> Come talk to me on Tumblr: bun-o-ween


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